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Re: Making more of the C standard library mandatory for freestanding implementations

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Paul Rubin <no.email@nospam.invalid> writes:

> Philipp Klaus Krause <pkk@spth.de> writes:
>
>> For many embedded users, memcpy() might be more useful and necessary
>> than long long or float.  Also, memcpy() is easier to implement than
>> support for long long or float.  Still the latter are currently mandatory
>> for freestanding implementations, while the former is not.
>
> Forth has a core wordset (basically a library) and a bunch of separate
> optional wordsets, each of which is standardized.  Floating point
> arithmetic is an optional wordset so it's fine if your implementation
> doesn't have it.  But if you do choose to supply floating point
> features, the standard says what those features should do, so you don't
> have to make it up as you go along.
>
> Maybe C could use a similar approach.

What I like about your idea is the notion that an interface is
standardized, and an implementation gets a binary choice,
either to provide it as specified, or just not to provide it.

To make that idea work for case under discussion here (ie, for
string functions), I think that needs to be augmented in two
ways.  One, it needs to be more fine grained than just all of
<string.h>.  Two, it needs to include a way for a program source
to inquire about whether any particular function has been
provided -- probably done using preprocessor symbols -- so that
the program can adapt to different environments, and do that
automatically, without needing to have a separate configuration
step.

For example, under this scheme, we might do this:

    // File "fs_string.h"    

    #include <string-optional.h>   // string.h optional subset

    #if ! _Provides_strlen
    extern size_t strlen( const char * );
    #endif

    ...

    // File "fs_string.c"

    #include "fs_string.h"

    #if ! _Provides_strlen
    size_t
    strlen( const char *s ){
        size_t r = 0;
        while(  *s++  )  r++;
        return  r;
    }

    #endif

Now the rest of the program can simply #include "fs_string.h",
and use strlen() just as it would if strlen() was supplied
by the implementation.

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Making more of the C standard library mandatory for freestanding implementations Philipp Klaus Krause <pkk@spth.de> - 2020-05-06 18:19 +0200
  Re: Making more of the C standard library mandatory for freestanding implementations Grant Edwards <invalid@invalid.invalid> - 2020-05-06 16:47 +0000
    Re: Making more of the C standard library mandatory for freestanding implementations Philipp Klaus Krause <pkk@spth.de> - 2020-05-06 19:16 +0200
      Re: Making more of the C standard library mandatory for freestanding implementations Grant Edwards <invalid@invalid.invalid> - 2020-05-06 18:10 +0000
        Re: Making more of the C standard library mandatory for freestanding implementations James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-05-06 15:10 -0400
          Re: Making more of the C standard library mandatory for freestanding implementations Richard Damon <Richard@Damon-Family.org> - 2020-05-06 16:08 -0400
            Re: Making more of the C standard library mandatory for freestanding implementations Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-05-06 13:22 -0700
              Re: Making more of the C standard library mandatory for freestanding implementations Richard Damon <Richard@Damon-Family.org> - 2020-05-06 22:29 -0400
                Re: Making more of the C standard library mandatory for freestanding implementations David Brown <david.brown@hesbynett.no> - 2020-05-07 15:43 +0200
              Re: Making more of the C standard library mandatory for freestanding implementations Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-05-07 06:08 -0700
            Re: Making more of the C standard library mandatory for freestanding implementations Philipp Klaus Krause <pkk@spth.de> - 2020-05-06 22:36 +0200
              Re: Making more of the C standard library mandatory for freestanding implementations Grant Edwards <invalid@invalid.invalid> - 2020-05-06 20:57 +0000
              Re: Making more of the C standard library mandatory for freestanding implementations Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2020-05-06 23:25 +0200
                Re: Making more of the C standard library mandatory for freestanding implementations Grant Edwards <invalid@invalid.invalid> - 2020-05-06 21:34 +0000
                Re: Making more of the C standard library mandatory for freestanding implementations Philipp Klaus Krause <pkk@spth.de> - 2020-05-07 10:17 +0200
                Re: Making more of the C standard library mandatory for freestanding implementations Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2020-05-07 18:45 +0300
                Re: Making more of the C standard library mandatory for freestanding implementations Philipp Klaus Krause <pkk@spth.de> - 2020-05-07 10:16 +0200
                Re: Making more of the C standard library mandatory for freestanding implementations Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2020-05-07 21:39 +0200
                Re: Making more of the C standard library mandatory for freestanding implementations Philipp Klaus Krause <pkk@spth.de> - 2020-05-07 21:44 +0200
                Re: Making more of the C standard library mandatory for freestanding implementations Paul Rubin <no.email@nospam.invalid> - 2020-05-07 12:54 -0700
                Re: Making more of the C standard library mandatory for freestanding implementations Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-05-08 08:38 -0700
                Re: Making more of the C standard library mandatory for freestanding implementations Philipp Klaus Krause <pkk@spth.de> - 2020-05-08 21:30 +0200
                Re: Making more of the C standard library mandatory for freestanding implementations Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-05-30 02:04 -0700
                Re: Making more of the C standard library mandatory for freestanding implementations Philipp Klaus Krause <pkk@spth.de> - 2020-08-04 10:58 +0200
                Re: Making more of the C standard library mandatory for freestanding implementations Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-08-04 07:35 -0700
          Re: Making more of the C standard library mandatory for freestanding implementations Philipp Klaus Krause <pkk@spth.de> - 2020-05-06 22:34 +0200
            Re: Making more of the C standard library mandatory for freestanding implementations upsidedown@downunder.com - 2020-05-07 09:13 +0300
            Re: Making more of the C standard library mandatory for freestanding implementations Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2020-05-07 18:47 +0300
              Re: Making more of the C standard library mandatory for freestanding implementations Grant Edwards <invalid@invalid.invalid> - 2020-05-07 15:51 +0000
                Re: Making more of the C standard library mandatory for freestanding implementations Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2020-05-08 10:09 +0300
    Re: Making more of the C standard library mandatory for freestanding implementations Florian Weimer <fw@deneb.enyo.de> - 2020-05-08 18:48 +0200
      Re: Making more of the C standard library mandatory for freestanding implementations Andrew Smallshaw <andrews@sdf.org> - 2020-05-08 17:01 +0000
        Re: Making more of the C standard library mandatory for freestanding implementations Philipp Klaus Krause <pkk@spth.de> - 2020-05-08 20:05 +0200
  Re: Making more of the C standard library mandatory for freestanding implementations upsidedown@downunder.com - 2020-05-07 08:59 +0300
  Re: Making more of the C standard library mandatory for freestanding implementations Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-05-07 06:14 -0700
    Re: Making more of the C standard library mandatory for freestanding implementations Philipp Klaus Krause <pkk@spth.de> - 2020-05-07 21:38 +0200
      Re: Making more of the C standard library mandatory for freestanding implementations Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-05-08 12:03 -0700
        Re: Making more of the C standard library mandatory for freestanding implementations Philipp Klaus Krause <pkk@spth.de> - 2020-05-08 21:15 +0200
        Re: Making more of the C standard library mandatory for freestanding implementations Philipp Klaus Krause <pkk@spth.de> - 2020-05-08 21:27 +0200
          Re: Making more of the C standard library mandatory for freestanding implementations Jakob Bohm <jb-usenet@wisemo.com.invalid> - 2020-05-15 15:13 +0200
        Re: Making more of the C standard library mandatory for freestanding implementations David Brown <david.brown@hesbynett.no> - 2020-05-09 00:25 +0200

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